I am new to Trello and not too technology-savvy so thank in advance for your help.
How can I change the label or title of my lists?

The three default lists are To Do/Doing/Done, but I would prefer to use the board in a different way, using each list to organize a different component of the overall project. There was this question asked and the answer was that lists cannot be re-labelled.

However, on the Trello Development board the lists are labelled Ideas/Known Issues/Next up, etc. I saw another user's screenshot where her lists were labelled Idea Pipeline and Planning.

Only Cards can be labelled, labelling in Trello means the Card is assigned to a category (represented by a coloured "tab" at the top of the Card).

Lists can however be renamed (their title changed) by simply double-clicking on the title, which puts it into Edit mode.
When you create a new list (using Options -> More -> Add List from the right-hand-side menu bar) you can specify it's title.